Starting and operating circuits and devices for electric discharge devices



Feb. 19, 1952 P WA ET 2,586,401

GU STARTING AND OPERATING CIRCUITS AND DEVICES FOR ELECTRIC DISCHARGEDEVICES Filed May 20, 1948 lm ervtorz Philippe Wagget b5 a 15 PatentedFeb. 19, 1952 STARTING AND OPERATING CIRCUITS AND DEVICES FOR ELECTRICDISCHARGE DE- VICES Philippe Waguet, Paris, France, assignor to GeneralElectric Company, a corporation of New York Application May 20, 1948,Serial No. 28,225 In France June 14, 1947 4 Claims. 1 This inventionrelates to electric discharge devices of the type employing ionizablemediums such as gases or vapors, and more particularly to starting andoperating devices and circuits there for.

An object of my invention is to provide a new I A feature of myinvention is the provision of 2 continuous voltage impulses to anauxiliary elec trode for initiating a discharge between the mainelectrodes of the devices. Consequent upon this feature is the advantageof immediate starting of the lamp upon the closing of an individual control switch, since starting impulses are at all times available. Afurther feature of my invention is the utilization of alternatingcurrent derived from the direct current source for providing continuousheating of the filamentary electrodes.

My invention is of general applicability wherever it is desired tooperate fluorescent lamps from a direct current supply. It has beenfound particularly useful in the illumination of vehicles and railroadcars having compartments or individual roomettes for the passengers. Thefeature of instantaneous starting of the individual fluorescent lamps isadvantageous in such applications for meeting the separate requirementsof the individual passengers. cussion of various circuits which may beutilized in operating fluorescent lamps from a direct current supply,reference is made to my copending U. S. application No. 28,223, filedMay 20, 1948. Other applications and improvements in such circuits aredisclosed in my copending U. S. applications Nos. 28,224 and 28,226,filed May 20, 1948, and 33,385, 33,386, and 33,387, filed June 16, 1948.All of the above-mentioned applications are assigned to the sameassignee as the present invention.

For a better understanding of my invention reference may be had to thefollowing description taken in connection with the accompanying drawingand its scope will be pointed out in the appended claims. The drawing isa diagrammatic view of an electric discharge device and a starting andoperating circuit therefor incorporating my invention.

In accordance with my invention, a continuous For a more completedisseries of starting impulses is provided to an auxiliary electrodemounted adjacent an electric discharge device, in combination withcontinuous heating of the filamentary electrodes thereof. The electricdischarge devices are connected in parallel across a direct currentsource of supply while at the same time an auxiliary source ofalternating current is made available for the heating of filamentaryelectrodes used as-cathodes.

This device, which is particularly applicable to the lighting ofrailroad car compartments, does not eliminate the flickering of lampswhich have become defective; however, it offers the economic advantageof requiring only one time-delay relay for each railroad car.

When all the lamps of a carriage are to be lighted, the voltage impulsesare applied to auxiliary electrodes mounted adjacent the lamps a fewseconds after voltage hasbeen applied to the entire group of lamps. Thisresults in a deferred general illumination when the feeder switchcontrolling the lamp circuits of a whole carriage is first closed, butwhen a lamp in a compartment is to be lighted, the voltage impulses areapplied at the same moment when the individual control switch is closed,so that the individual ignition is instantaneous.

Referring to the drawing, I have there illustrated one embodiment of myinvention as applied to electric discharge devices I, I. The electricdischarge devices I, I, such as fluorescent lamps therein illustrated,comprise elongated tubular or cylindrical envelopes 2, 2' having sealedinto the ends thereof filamentary electrodes 3, 4 and 5, 6. Thesefilamentary electrodes may comprise coils, preferably in the form ofcoiled coils of tungsten wire activated with oxides of alkaline earthmetals, such as a mixture of barium and strontium oxides. The envelopes2, 2 may contain gaseous atmospheres such as a rare gas like neon,argon, or mixtures thereof, at a pressure of a few millimeters and asmall quantity of mercury which, during the operation of the lamps, hasa low pressure of the order of 10 microns. Devices I, I may be lowpressure positive column lamps of a' fluorescent type provided with asuitable phosphor or fluorescent coating. This fluorescent coating, uponexcitation by the radiation produced by an electric discharge betweenthe electrodes, transforms a shorter wave radiation due to the dischargeinto longer wave radiation, such as radiation within the visible range.Metal cups 1, 8 and 9, l 0 serve to intercept particles of emissivematerial sputtered from electrodes 3, 4 and 5, B, respectively. Thesecups are usually connected, either outside or inside of the lamps, tothe extremities of the electrodes. A number of advantages result fromthe connections between the electrodes and the corresponding cups,namely, utilization of the cups 8 and II] as anodes and eliminating thedisintegration by ionic bombardment of electrodes 4 and 6, utilizationof lamps that are usually employed with alternating current dischargecircuits, reduction of operating voltage, doubling the life of lamps byusing successively the two filamentary electrodes, i. e., by turning thelamps around when one of the filaments becomes inoperative.

Devices I, I are connected across a suitable direct current power supplycircuit II, II for supplying current thereto through stabilizingresistances I2, I2. Resistances I2, I2, for example, may be iron ortungsten wire enclosed in hydrogen. A manual make-and-break controlswitch I3 may be used to connect devices I, i to. the power supply II,II'. A starting circuit 14, M" is connected across the direct, currentsupply II, II and comprises an inductance it, a switching means I6, anda resistance Ii. Auxiliary electrodes I8, I8, mounted adjacent devicesI, I, are connected to acommon point !9 intermediate inductance I5 andswitching means I6 through a time-delay relay or second switching means23. Resistance I'I serves to regulate the value of the potential whichthe auxiliary electrodes 18, I8 assume. The time-delay relay orswitching means comprises a coil 2!, which is connected across theterminals of the direct currentsupply H, I I through the manualmakeand-break switch I3, and switch contacts 22, actuated by the coil 2iand located between point i9 and the wire which the auxiliary electrodesit, I8. have in common. A pair of double-pole switches 23, 23'comprising contactors 24a, Zeb and 24a and 24b, respectively, areassociated with devices I, I, respectively, Contactors 24a, 240: are inseries with the discharge circuits of devices .I, l, respectively, andcontactors 24b, 2419' are in series with the connections betweenjunction point IS and auxiliary electrodes lag-I8, respectively, so-thatthe starting voltage impulses are applied therethrough.

A transformer 25 comprising a-primary winding sectionZEandacenter-tapped secondary winding section 2-? is connected across analternating current supply and serves to heat filamentary electrodes 3and 5 and to continue to heat these electrodes as long as switch I3remains closed. The center-tap of the secondary section 27 is connectedto the negative terminal II' of the direct current source of supply bymeans of switch IS.

The switching means IS which serves to break the inductive startingcircuit consistsv of av rotary switch which ismounted on the shaft of aconverter. 28..which supplies transformer 25 with an alternatingcurrent. Switching means It may comprise a rotary switch employing apair of brusheseachsliding ona ring. One of these rings may be entirelymetallic; the other ring being half metallic and half insulating, andthe metal parts of the two rings may be electrically interconnected. Inthe drawing, the rotary switch is consists of two brushes 29 and 30which slide on one metal ring 3| comprising an insulating circularsector 32. A pair of fuses 33, 3 3 in the discharge circuits protect theelements oi the heat ra orme 5. n he ca i a ho q -F ll l he h$ m9 .1! 1lfilamenta 3 rosie 3 n 5.-

The circuit and device indicated in the drawing operate as follows: Inthe rest position, the contactor 22 of relay 20 is open; as soon as themanual make-and-break switch I3 is closed the converter 28 starts,filamentary electrodes 3 and 5 serving as cathodes are heated, coil 2Iof the time-delay relay 2% is energized and the rotary switch IE sets upvoltage impulses at the point I9. After one or several seconds, thetime-delay relay 20 begins to operate and closes contactor 22. Switches23, 23 in the discharge circuits of devices I, I are normally closed andthus the voltage impulses are imparted to the corresponding auxiliaryelectrodes I8, I8 which causes devices I, I to become conductive.

Inasmuch as the filamentary electrodes 3 and 5 of devices I, I,respectively, are continuously heated, switches 23, 23 may be opened andthe devices I, I instantaneously lighted again when these switches areagain closed.

It is quite evident that the invention may be applied to other purposesbesides the one which has been mentioned here, i. e., the lighting ofrailway carriages. It can be applied particularly well to the lightingof motion picture studios or of television studios, wherein it isdesirable, under certain circumstances, to utilize direct current forfluorescent lighting rather than alternating current so as to eliminatethe possibility of stroboscopic flickering. The appended claims are,therefore, intended to cover any modifications coming within the truespirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. Apparatus for operating a ga eous luminous electric discharge deviceof the type including a main filamentary electrode and a cooperatingmain electrode, comprising: a unidirectional voltage source, a twocontactor switch, a ballast resistance, and an auxiliary dependentsource of alternating voltage; connections for continuously energizingsaid filamentary electrode from said alternating source; a dischargecircuit including said device, said ballast resistance and one contactorof said switch connected in series-across said unidirectional source; astarting circuit comprising a limiting resistance, automatic switchingmeans, and an inductance, serially connected across said unidirectionalsource, said switching means continuously making and breaking saidstarting circuit to produce starting impulses; and an auxiliary startingelectrode on said device. said auxiliary electrode being connectedthrough a second contactor of said switch, to the junction of saidswitching means with saidinductance, said device being therebycontinuously supplied with said starting impulses upon the closing ofsaid control switch. 7

2. Apparatus for operating a gaseous luminous electric discharge deviceof the type including a main filamentary electrode and a cooperatingmain electrode, comprising: a unidirectionalvoltage source, a twocontactor control switch, a ballast resistance, and an auxiliarydependent source of alternating voltage; a transformer having a primarywinding connected to said alternating source, and a secondary windingconnected to said filamentary electrode for supplying heating currentthereto, said secondary winding having a center tap; a discharge circuitincluding said device connected to one side of said unidirectionalsource through said center tap and to the other side of saidunidirectional source through said ballast resistance and one contactorof a said control switch; a starting circuit comprising a limitingresistance, switching means continuously making and breaking saidstarting circuit and an inductance serially connected across saidunidirectional source; an auxiliary starting electrode mounted on saiddevice intermediate the ends thereof; and a connection from saidauxiliary electrode, through the other contactor of said control switch,to the junction of said inductance with said switching means forsupplying starting impulses to said device upon the closing of saidcontrol switch.

3. Apparatus for operating a plurality of gaseous luminous electricdischarge devices of the type including a main thermionic electrode anda cooperating main electrode, comprising: a unidirectional voltagesource and an auxiliary dependent source of alternating voltage; aplurality of two contactor control switches and ballast resistors; atransformer having a primary winding connected to said alternatingsource, and a secondary winding connected to said thermionic electrodesin parallel for supplying heating current thereto, said secondarywinding having a center tap; a plurality of discharge circuits includingsaid devices connected to one side of said unidirectional source throughsaid center tap, and to the other side of said unidirectional sourcethrough individual ones of said ballast resistors and the firstcontactors of said control switches; a starting circuit comprising alimiting resistance, continuously operative switching means for makingand breaking said starting circuit, and an inductance serially connectedacross said unidirectional source; auxiliary starting electrodes mountedon said devices intermediate the ends thereof; and connections from saidauxiliary electrodes, through the second contactors of said controlswitches, to the junction point of said inductance with said switchingmeans for supplying starting impulses to said devices upon the closingof their associated control switches.

4. Apparatus for operating a plurality of gaseous luminous electricdischarge devices, of the type including a main filamentary electrodeand a cooperating main electrode, comprising: a principal source ofunidirectional voltage, an auxiliary dependent source of alternatingvoltage in the unidirectional source; a plurality of ballast resistorsand two contactor control switches; a

transformer having a primary winding connected to said converter and asecondary winding connected to said filamentary electrodes in parallelfor supplying heating current thereto, said secondary winding having acenter tap; a plurality of discharge circuits including said devicesconnected to one side of said unidirectional source through said centertap, and to the other side of said unidirectional source throughindividual ones of said ballast resistors and first contactors of saidcontrol switches; a starting circuit comprising a limiting resistance, arotary switch mechanically coupled to said converter for making andbreaking said starting circuit, and an inductance, serially connectedacross said unidirectional source; auxiliary starting electrodes mountedon said devices intermediate the ends thereof; and connections from saidauxiliary electrodes, through the other contactors of said controlswitches, to the junction point of said inductance with said rotaryswitch for supplying starting impulses to said devices upon the closingof their associated control switches.

PHILIPPE WAGUET.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

